Virtual worlds, those that recreate or represent real three dimensional (3D) space can be used as environments to demonstrate, coach, and guide user body motion for the purposes of exercise and rehabilitation instruction. These digital environments can employ the use of an animated character, or avatar, in addition to other on-screen feedback to provide real time instruction and visual representation of motion. This motion specifically refers to limb or body motion. Using various camera technologies, including both RGB and depth cameras, a second ‘user’ animation can be placed into the virtual 3D environment to provide side by side, preferably real time, representation of real user limb and body motion, including physical orientation to the camera, real world surroundings, and location within the virtual environment (including perceived interaction with virtual elements).
Systems that employ virtual worlds that present motion instruction exhibit a common problem, namely it is difficult for the user to understand how their movement in the “real” world links to their digital representation (e.g. avatar, character, animation, etc.) in the “virtual” world. In particular, there can be difficulty determining which limb characters in a virtual world are using. In many applications (such as video games), products resolve this by “mirroring” the avatar (in the virtual world) with the player (in the real world). So when the player moves their left arm, for example, the avatar will move their right, similar to the effect observed when individuals move while watching their reflection in front of a mirror.
However, for more complex and/or clinically specific motions, this can be confusing for several reasons. First, if people are unfamiliar with game conventions, they can notice that the avatar is instructing them to move the “wrong” limb, that is, if the instruction is intended to have the user raise their right arm, the user raises their left arm as a result of the instructional avatar using their left arm. Second, the patient may need to see multiple angles of the digital avatar/coach to understand the motion properly. Third, for experiences using motion-tracking cameras (e.g. the Microsoft Kinect), the user may have to stand orthogonal (at an angle) to the camera so that their relevant limbs can be properly tracked. In those circumstances, the confusion can be greatly exacerbated.
The systems and methods described herein provide a novel solution to these problems.